//You are given the root of a binary tree containing digits from 0 to 9 only. 
//
// Each root-to-leaf path in the tree represents a number. 
//
// 
// For example, the root-to-leaf path 1 -> 2 -> 3 represents the number 123. 
// 
//
// Return the total sum of all root-to-leaf numbers. Test cases are generated so
// that the answer will fit in a 32-bit integer. 
//
// A leaf node is a node with no children. 
//
// 
// Example 1: 
//
// 
//Input: root = [1,2,3]
//Output: 25
//Explanation:
//The root-to-leaf path 1->2 represents the number 12.
//The root-to-leaf path 1->3 represents the number 13.
//Therefore, sum = 12 + 13 = 25.
// 
//
// Example 2: 
//
// 
//Input: root = [4,9,0,5,1]
//Output: 1026
//Explanation:
//The root-to-leaf path 4->9->5 represents the number 495.
//The root-to-leaf path 4->9->1 represents the number 491.
//The root-to-leaf path 4->0 represents the number 40.
//Therefore, sum = 495 + 491 + 40 = 1026.
// 
//
// 
// Constraints: 
//
// 
// The number of nodes in the tree is in the range [1, 1000]. 
// 0 <= Node.val <= 9 
// The depth of the tree will not exceed 10. 
// 
// Related Topics 树 深度优先搜索 
// 👍 364 👎 0

package leetcode.editor.cn;
 class P129SumRootToLeafNumbers {
    public static void main(String[] args) {
        Solution solution = new P129SumRootToLeafNumbers().new Solution();
    }
    //leetcode submit region begin(Prohibit modification and deletion)
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    int sum = 0;

    public int sumNumbers(TreeNode root) {
        sumNumbers(root, 0);
        return sum;
    }

    private void sumNumbers(TreeNode root, int curSum) {
        if (root == null) {
            return;
        }
        int oriSum = curSum;
        curSum = curSum * 10 + root.val;
        if (root.left == null && root.right == null) {
            sum +=curSum;
        }
        sumNumbers(root.left, curSum);
        sumNumbers(root.right, curSum);
        curSum = oriSum;
    }
}
//leetcode submit region end(Prohibit modification and deletion)

}